All in all cost was upward of $60, but it takes quite a few fittings to go from 4" pvc to the 3/4" pvc I used for the main body.

The thing is a monster and shoots for far longer than any super soaker I've had the pleasure of owning. I'll get pics when I can, I guess, but I'd almost prefer to paint it first... Still need to come up with a water backpack, though. It'll plow through stuff pretty quick. I can put over a half gallon in the twin pressure chambers.

At the 3" point, most users prefer to add more pressure chambers, which has a similar effect to using a 4" chamber instead. (This is mostly for costs, I guess.) Either way, nice job getting it to work; I'll have to check out the pics/vids when posted.

For me, 4" was way cheaper. We have a ton left over from when I built an artillery-scale PVC spud gun... Close to 10' long overall, has a ~3' combustion chamber and a ~7' barrel. Can lob a golf ball over a mile... It's fun!

Will have to get vids. Currently experimenting with different barrel lengths. Stream is a bit short at the moment, have a barrel about as long as two fittings, not a very laminar stream.